While the closing of the airways has already laid waste to the immediate plans and business of industry, the arts and world leaders, the possibility that it could drag on for days, if not weeks, is raising concerns about the longer-term consequences for public health, military operations and the world economy.

The damage will roll through to farms, retail establishments and nearly any other business that depends on air cargo shipments. Fresh produce will spoil, and supermarkets in Europe, used to year-round supplies, will begin to run out.

Economists do not believe there is an immediate danger, but "if it really drags on another week," disrupting global supply chains, "that could be really serious," said Peter Westaway, chief economist for Europe at the Nomura investment bank.

Scientists aren't holding out much hope of an immediate end.

"There doesn't seem to be an end in sight," Icelandic geologist Magnus Tumi Gudmundsson said Saturday.

"The activity has been quite vigorous overnight, causing the eruption column to grow."

That massive plume of volcanic ash has now spread over much of northeastern Europe, extending to northern Italy and east to Ukraine. The ash, composed of superfine particulate matter, can seize up jet engines, making air travel impossible anywhere in the ash plume.

As a result, Eurocontrol, the European air navigation safety agency, closed airspace over 23 countries, including Poland, where the state funeral of Lech Kaczynski and his wife – killed in an air crash with 94 others in western Russia April 10 – is being held Sunday.

Prime Minister Stephen Harper and U.S. President Barack Obama are among the international leaders who have cancelled plans to attend, citing the inability to get to Krakow.

It was no different for anyone else attempting to fly into or out of the affected zone, whether by presidential jet or commercial carrier.

FedEx and other shippers are grounded throughout much of Europe.

Scores of U.S. military resupply flights for Afghanistan, many of which pass through European airspace, have been grounded or redirected, and combat casualties from the region, normally sent to the giant U.S. air base and hospital at Ramstein, Germany, were being flown directly to the United States.

At New York's Kennedy Airport, "it's like a refugee camp," said Rhiannon Thomas, who has been told it may be days before she gets back home to Birmingham, England.

In Toronto, more than 25 flights arriving from Amsterdam, London, Paris, Brussels, Frankfurt and other European cities were cancelled Saturday, and a similar number of departures for the region were scrubbed.

It doesn't promise to be much better Sunday – or, for that matter, Monday.

"It's up to air traffic controllers in the U.K.," said Trish Krale, a spokesperson for the Greater Toronto Airports Authority.